I had a lot of money to waste so I got a bunch of keys and opened a bunch of crates. I got one of all the strange items and an unusual hat! My highest ranked is my rocket launcher at 361 kills. I believe that its called a "Gore-Splattered Rocket Launcher".
I'm glad they finally added something arguably worth buying keys for, those unusual hats are so rare.
Just found this if you want to see the different rank names.